Scientists hoping to use Wednesday's total solar eclipse to gain a rare glimpse of the workings of the sun's atmosphere were left lamenting 'the one that got away'. A team of mainland astronomers had gathered in a carefully chosen spot in Anji county, Zhejiang , hoping the longest eclipse in a century would reveal one of the great mysteries of the sun: why its atmosphere is 200 times hotter than the surface. But then the clouds rolled in and spoiled their plans. 'The clouds have completely ruined our scientific observations, which required high levels of precision,' said Qu Zhongquan, a senior researcher at Yunnan Astronomical Observatory under the Chinese Academy of Sciences. 'My disappointment is beyond description.' After screening every city in the eclipse's shadowy path, Professor Qu and his team decided out-of-the-way Anji was the perfect place to conduct their research. During the week before the eclipse, they set up an expensive observation platform, calibrated specially designed telescopes and did test runs on hardware and software to make sure everything would work perfectly on the big day. Their aim was to capture the solar flash polarisation spectrum - the spectrum of sunlight during the eclipse - which they hoped would lead to a solution to the heating conundrum, known as the coronal heating problem. The coronal heating problem has troubled physicists and astronomers for more than seven decades. 'We know that the more distant an object is from the heat source, the cooler it should be. But the solar atmosphere - the corona - is 200 times hotter than the surface of the sun itself,' he said. 'Researchers have proposed many brilliant ideas trying to explain this counter-intuitive phenomenon. But none could find solid evidence to back up their claim.' Professor Qu said the solar flash polarisation spectrum was a new way to look at the internal structure of the corona and had the potential to provide interesting clues to help solve the mystery. Professor Qu and his team was the world's first to record the solar flash polarisation spectrum during a total eclipse in Gansu province last year. 'The success increased our confidence. Our equipment and technology was proved to be reliable and the data we obtained was of superior quality,' he said. 'But there were also a few regrets. For example, we missed an important green spectrum, the image resolution was not the highest and the sampling size was not very big. So we hoped to make up for it this time.' But the clouds had generated so much distortion that the data set was almost useless, he said. Despite the failure, the professor said he would continue to track eclipses. 'We can easily produce an artificial total solar eclipse by using a coronagraph on satellites,' he said. 'But no matter how much we improve our equipment, the quality of a natural eclipse is much better, because nothing man-made can be as big and as far away as the moon.' Then he added after a pause: 'When the weather is good.'